Connecting to Aluminum

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  #1  
Old 03-10-12, 12:23 AM
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Connecting to Aluminum

Hello, everyone.

I'm thinking it might be a good idea to put aluminum to copper splices in metallic handy boxes, exposed in the attic.

Although I apply no-ox freely, I'm still leery of stuffing such a splice in a crowded switch box. Wouldn't it be better to isolate the splices, so that if there is charring, the heat is confined to the handyboxy? That would also mean that in the actual working boxes, all the wires would be of the same type, and The Next Guy wouldn't have to worry about finding the tube of No Ox and getting that gunk all over everything.

I don't mind the extra expense and time; it's my house. I'm cleaning up numerous problems anyway, and whenever I do anything, I rip out all the AL wiring I can get a hold of.
 
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Old 03-10-12, 03:40 AM
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Welcome to the forums! Making your splices in the attic is a good idea, running copper down to the receptacles and switches, and to the point of use lights. You can't use a switch box for such a splice/tap. You will need to use the appropriately sized junction box for the wire fill calculations and provide a cover, and make sure it is protected from abuse.
 
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Old 03-10-12, 08:01 AM
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Thanks for the prompt response.

"You can't use a switch box for such a splice/tap."

Oh. Dear.

The Last Guy added in quite a bit of copper wiring, and I've found several such splices in switch/outlet boxes, often as pigtails on a replacement device.

"protected from abuse"

Am I correct in assuming that in the attic, this means out of the way, unlikely to be stepped on, tripped over, or brushed against, but still accessible for repairs and upgrades?

Is it permitted to place such a splice box on the side of a joist, facing upwards but not where I or The Next Guy is likely to step? The cover facing up makes it much easier to work on than facing sideways; it's not covered by insulation, and you can see directly down into the box.
 
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Old 03-10-12, 09:22 AM
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I have asked for a clarification from Larry, but if you are asking about using a typically single gang box like you would use for a receptacle or switch, there should be no issue using these for a splice. Keep they out of the way and perhaps mark the area somehow.
 
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Old 03-10-12, 09:52 AM
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I'm specifically talking about dedicating drawn metal handy boxes with drawn metal blank covers to make these splices. (These are the seamless boxes with rounded corners.) I'm thinking that if there is ever a problem with the splice, that's the best way to contain the smoldering.

I'm faced with two situations: Copper feed running to an old box with aluminum wiring that daisy chains to the rest of the circuit, and aluminum feed running to a new box with copper wire inside.
 

Last edited by oldwork; 03-10-12 at 09:56 AM. Reason: clarification
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Old 03-10-12, 10:49 AM
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Give up on the thought of metal handy boxes. They do not have enough space. A typical handy box may only have 8 cubic inches of volume.

Use a 20 or 22.5 cubic inch plastic box with a blank cover or use a 4x4 deep metal box.

When you see the size required by the listed connectors you will understand why.
 
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Old 03-10-12, 12:17 PM
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Jim, your last post sort of clarified my statement. Thanks for the catch. You can use the boxes, but they must be of sufficient size to accommodate the splice/taps. Most of the time they are not. Metal handy boxes is what I was envisioning. Oldwork, sorry for the confusion. It takes a team to keep all of us on the right track.
 
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Old 03-10-12, 01:46 PM
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Thanks, everyone. I should have realized this question was not as simple as I thought.

Originally Posted by pcboss View Post
Give up on the thought of metal handy boxes.
...
When you see the size required by the listed connectors you will understand why.
I was planning to use 4 x 2-1/8 x 1-7/8 drawn metal boxes, which my copy of Mullin's Electrical Wiring Residential 13th ed. (fig. 2-19 from NEC table 370-16a) lists as having a volume of 13 in[SUP]2[/SUP], allowing a fill of 5 #12 conductors.

In each box, I would only splice together two 12-2 NM cables, a wire count of 5, given that all ground wires together count as one.

I cannot find anything suggesting that Ideal's TWISTER Al/Cu wire nuts add to the fill count.

But horrible thought! Mullins reminds me that any number of "internal clamps" sadds 1 to the count. I'll be using Arlington's Black Button NM connectors that push in from the outside and take up little space; do they count?

And even more horrible thought!! the aluminum wire is, of course, one step heavier for the same current rating. But doesn't that "same current rating" imply that I'm dealing with the same heating potential, regardless?

I acknowledge that at this point, the situation is so marginal that I really should go to Orange Cube one more time for yet another nest of boxes and give those splices a little breathing room. (On my first trip, I failed to notice that I was getting 3/4" knockouts instead of 1/2".)

(In any event, I've got to be making things better by ensuring that the splice is isolated in the attic, rather than stuffed into a device box in the wall.)
 
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Old 03-10-12, 02:39 PM
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The NEC does not add an allowance for wire connectors. However, the Twisters are rather large and the older AL does not like to be bent before failing from fatigue. You still need to have room to tuck everything into the box.

I would not consider the cable clamps to need an allowance.
 

Last edited by pcboss; 03-10-12 at 04:37 PM.
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Old 03-10-12, 03:34 PM
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I cannot find anything suggesting that Ideal's TWISTER Al/Cu wire nuts add to the fill count.
I would suggest avoiding the Twister by Ideal when possible, but don't totally condemn them. There is an ongoing debate about them being appropriate for use with aluminum and copper wiring although they are still U.L. Listed.

Aluminum Wiring Twist-on Connector Debate about the Ideal 65 "Twister" for Aluminum Wiring Repair

I would prefer to see you use AlumiConn connectors. They have a much better success rate.

Amazon.com: King Innovation AlumiConn: Home Improvement
 
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Old 03-10-12, 04:39 PM
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I would second the vote for the Alumi-conns. The instructions call for a torque screwdriver to be used.
 
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Old 03-10-12, 09:17 PM
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I would prefer to see you use AlumiConn connectors. They have a much better success rate.

Amazon.com: King Innovation AlumiConn: Home Improvement
Holy.

Smokes.

The links you provided really kicked me down the rabbit hole. I thought I was doing well filling ordinary wirenuts with NoAlOx paste, per just about every book and website I've ever seen, and that I was ridin' Cadillac with the Barnies.

Gah.

Will splice the immediate repair with the #65 TWISTERS but will order a boxful of the Alumiconns, maybe even a torque screwdriver, and rework as many of these splices as I can find when I can.

Strong ratification of my policy to replace the aluminum wire wherever I can.

I am not happy to learn that the house is about to burn down. I've found a couple of charred splices with regular wirenuts before, but thought that they were due to careless installation. Indeed, as I poke around more on the web, I see that many failures are due to improper work, such as unlisted wire combinations.

Accordingly:
  1. Device and fixture boxes containing all aluminum wiring will not be disturbed, except to replace wirenuts with Alumiconns as the opportunity presents itself. Feeder splices will be made in the attic.
  2. Wherever practical, existing #10 aluminum wire will be replaced with #12 copper, especially on home runs.
  3. Each CO/ALR splice will be isolated in a separate 4 in[SUP]2[/SUP] drawn metallic box, with the cables secured using metallic clamps. Wherever possible, the boxes will be attached to uprights and oriented to facilitate inspection. Otherwise, they will be mounted on the inside face of a joist and will be kept clear of insulation.
  4. Wires will be fresh cut and stripped long.
  5. Wires will be coated with anti-ox compound from a sacrificial Ideal #65 TWISTER wirenut, then abraded with #240 wet or dry sandpaper.
  6. CO/ALR wire pair will be securely twisted together with pliers, then trimmed to 1/2 in. length. Further, a few turns will be made in the insulated portion of the wire to stabilize the splice. (Pretwisting is "recommended but not required" by Ideal.)
  7. A #65 wirenut will be applied using a wirenut driver.
  8. A blank cover plate will be installed on the box.
  9. When Alumiconns are in hand, they will replace the #65s. (I only have one, possibly two splices that must be made immediately; the rest will wait.)

There. Did I miss anything?

Dang it, I have a whole Spring of work to look forward to, before it gets too hot to go into the attic.

======

Anyone who's interested, here's the report on "Reducing the Fire Hazard in Aluminum-Wired Homes" [PDF] that seems to be the primary source for recommendations by inspection agencies and even the CPSC.

===

This outfit is apparently the factory outlet for Alumiconns. A box of 25 is "only" $79, about $3.20 each (v. Amazon, $3.26). That's enough for eight splices, plus one lost down a crack. A box of 100 comes to $3.11 each, and is probably what I'd need to do the house right.

They recommend the Wiha torque driver as being well-calibrated.

Amazon sells Wiha torque drivers for ~ $75; only a bit more than three times what I paid for my bag of 10 TWISTERS. Certainly cheaper than getting certified for and leasing AMP's crimp tool or doing a total rewire, and far less expensive than a new house and two or three funerals.

===

In addition to using a torque driver, I've seen several recommendations that the connector be held by "a tool" while tightening.
 

Last edited by oldwork; 03-10-12 at 10:49 PM.
  #13  
Old 03-11-12, 07:54 AM
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Wires will be coated with anti-ox compound from a sacrificial Ideal #65 TWISTER
There is no need to sacrifice a Twister to get the anti-ox compound. Just buy it at any big box store.

Ideal NOALOX 4 Oz. Anti-Oxidant Compound 30-026 at The Home Depot

Or Lowes store.

Shop IDEAL 4-Oz. Tube Noalox Anti-Oxidant at Lowes.com

Or, buy any brand that inhibits corrosion on aluminum conductors. Contax is a popular product by T&B at a lot of supply houses; Penetrox A Series is another brand by Burndy.

http://www.wescodirect.com/direct/im...334_elec08.pdf
 
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Old 03-11-12, 09:36 AM
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Did you really mean to clean the conductors after applying the anti-oxidant paste?

I agree with CJ, just buy a small bottle of Penetrox.
 
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Old 03-11-12, 02:25 PM
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I've lost the tab with these recommendations, but no, this isn't stuff I came up with on my own.

You use the stuff from inside a TWISTER because there are different anti-ox formulations, and apparently not all of them are compatible.

[update] Ferex, I just checked the MSDS' for TWISTERs and Penetrox.

TWISTERs use antimony trioxide and zinc dust in a polybutene base.

There are at least four Penetrox formulations. "A" is aluminum stearate. "E" is copper dust in castor oil. And so forth.
[/update]

You use anti-ox on the wet-dry sandpaper to keep the freshly scuffed wire from re-oxidizing.

My sense is that if you're using a wirenut at all, you're doing a marginal thing, so you give your self as much margin as possible.
 

Last edited by oldwork; 03-11-12 at 03:37 PM.
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